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Computers8 Ch4 3
 

Computers8 Ch4 3

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Chapter 4 - Part III

Chapter 4 - Part III

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    Computers8 Ch4 3 Computers8 Ch4 3 Presentation Transcript

    • Chapter 4 B.M.H The Central Process Unit
    • Learning Objectives
      • List the measures of computer processing speed and explain the approaches that increase speed.
        • Microprocessor speed
        • Memory cache
        • Flash memory
        • RISC computers
        • Parallel processing
      MIU P4-116
    • What makes a computer fast?
      • Factors
        • Microprocessor speed
        • Bus line size
        • Availability of cache
        • ( More sophisticated ones )
        • Flash memory
        • RISC computers
        • Parallel processing
      MIU
    • Computer processing speeds
      • The execution of an instruction
          • may be measured in
        • Millisecond : 1/10 3 of a second
          • very slow (old) computer
        • Microsecond : 1/10 6 of a second
        • Nanosecond : 1/10 9 of a second
          • modern computer
        • Picosecond : 1/10 12 of a second
      MIU
    • Computer processing speeds
      • Microprocessor speeds
        • are determined by
        • Microprocessor ’ s clock speed
        • MIPS
        • Megaflop
      MIU
    • Microprocessor ’ s clock speed
      • Usually expressed in
        • megahertz (MHz)
          • 10 6 of machine cycles per second
        • gigahertz (GHz)
          • 10 9 of machine cycles per second
        • Ex. a PC listed at 500MHz
          • : capable of handling 500*10 6 machine cycles/s
      •  Direct comparison of clock speeds
        • Meaningful only between identical microprocessors
      MIU
    • MIPS
      • One m illion i nstructions p er s econd
        • Ex. A computer with speed of 0.5MIPS
        • : execute 500,000 instructions per second
        • High-speed personal computer
        • : perform at 100 MIPS and higher.
      • A more accurate measure than clock speed
      MIU
    • Megaflop
      • One m illion flo ating- p oint operation per second
      • The ability of the computer to perform complex mathematical operation.
      MIU
    • Cache
      • Temporary storage area
        • Designed to speed up data transfer within the computer
      • Types
        • Memory cache
        • Disk cache ; chapter 6
      MIU
    • Memory cache
      • A relatively small block of very fast memory
        • Designed for the specific purpose of speeding up the internal transfer of data and software instructions.
        • The data and instructions stored in cache
        • : are most recently or most frequently used.
      • Types
        • Internal cache
        • External cache
      MIU
    • Memory cache MIU
    • Memory cache
      • Internal cache, Level 1 (L1) cache
        • In the processor
        • The fastest sort
        • Takes up precious space and increase the cost of the microprocessor
        • No more than 128KB
      • External cache, Level 2 (L2) cache
        • On separate chips
        • Probably 256KB or 512KB
        • SRAM technology
        • Cheaper and slower than L1 cache
        • much faster (and more expensive) than memory
      MIU
    • Flash Memory
      •  Memory : volatile
      •  Secondary storage : slow rate
      • Flash memory
        • nonvolatile RAM
        • Faster than secondary storage
          • Used in cellular phones, digital cameras, and digital music recorders
          • Replacing disks in some handheld computers
          • Being produced in credit card
          • Smaller than a disk drive
          • Require only half the power
      MIU
    • RISC Technology
      • Instruction set
        • a specific group of instructions that each type of CPU is designed to understand
          • such as ADD or MOVE
        • A single program instruction
          • May be made up of a substantial number of subinstructions, each of which must take at least one machine cycle
      • Instructions set computing types
        • CISC ( Complex instruction set computing )
        • RISC ( Reduced instruction set computing )
      MIU
    • RISC Technology
      • CISC ( Complex instruction set computing)
        • Many of the most complex instructions in the instruction set are rarely used
          • A problem to speedy performance
        • Intel ’ s Pentium family
      • RISC ( Reduced instruction set computing)
        • Small subset of instructions
        • Increase the speed
        • Programs in graphics and engineering areas
          • A significant performance advantage
        • PowerPCs and Alphas
      MIU
    • Parallel Processing
      • Serial processing
        • The execution of one instruction at a time
      • Pipelining
        • An instruction action doesn ’ t need to be completed before the next instruction action is begun.
          • An instruction : One fetch is complete for it and it moves to decode.
          • the next instruction : Fetch is begun for the next.
        •  Problem : a single electronic pathway (bus line) acts like a bottle neck.
      MIU
    • MIU
    • Parallel Processing
      • A method of using multiple processors at the same time
        • Many processor, each with its own memory unit, working at the same time
      • Ultimate speed solution
      • Capable of operating in term of teraflops
        • Trillions of floating-point instruction per second
          • Network server : with 4 to 16 processors
          • Supercomputer : with 100 or 1000 processors
      MIU